Where do you find information about linear algebra?

Okay, I'm sorry if I'm starting to annoy anybody, but I have posted a few things about planes and hyper-planes in the mathematics section. One was how to extend Euclid's fifth postulate to higher planes of arbitrary dimensions, and the recent one was about the intersection of two planes. I have been told that instead of referring to elementary geometry I should use linear algebra to solve these problems (which makes me a little sad since I can't use my formal axiomatic system in my way). I looked at the Wikipedia page about linear algebra and it looks like it is the algebra of vectors, vector spaces, and scaling factors (numbers to multiply vectors). I have read a little bit into abstract algebra, and I've learned that there are many different types of algebras and have looked into properties of rings and groups, and now I am looking at a specific one. I have read the axioms of linear algebra and have noted their similarities and differences with elementary algebra. But that was as far as I have gotten (besides basic properties of maps and other things on that page). I've found some books on linear algebra, but no websites. Are there any websites that help?